View MAX3323E_278647.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-2667; Rev 1; 1/03
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
General Description
The MAX3322E/MAX3323E 3.0V to 5.5V powered EIA/TIA-232 and V.28/V.24 communications interfaces are designed for multidrop applications with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection. All RS-232 inputs and outputs are protected to 15kV using the IEC 1000-4-2 Air-Gap Discharge method, 8kV using the IEC 1000-4-2 Contact Discharge method, and 15kV using the Human Body Model. The MAX3322E/MAX3323E have pin-selectable 5k/high-impedance RS-232 receivers. These devices are capable of receiving data in high-impedance mode. In multidrop applications, one receiver has a 5k input resistance, while the other receivers are high impedance to ensure the RS-232 standard is observed. Logic control permits selection of the functional mode: high impedance or RS-232 standard load. The transmitters are enabled by logic control to allow the multiplexing of the inputs to a single UART. A proprietary low-dropout transmitter output stage enables true RS-232 performance from a 3.0V to 5.5V supply with a dual charge pump. The charge pump requires only four small 0.1F capacitors for operation from a 3.3V supply. The MAX3322E/MAX3323E are capable of running at data rates up to 250kbps while maintaining RS-232-compliant output levels. The MAX3322E/MAX3323E have a unique VL pin that allows operation in mixed-logic voltage systems. Both input and output logic levels are pin programmable through the VL pin. The MAX3322E is a 2Tx/2Rx device for hardware handshaking in standard RS-232 mode, and the MAX3323E is a 1Tx/1Rx, required in most multidrop applications. The MAX3322E is offered in a space-saving TSSOP package. The MAX3323E is offered in 16-pin DIP and space-saving TSSOP packages.
Features
o Pin-Selectable 5k/High-Impedance Receivers o Transmitter Outputs Three-Stated by Logic Control o VL Pin for Compatibility with Mixed Voltage Systems o 1Tx/1Rx (MAX3323E) or 2Tx/2Rx (MAX3322E) Versions o 250kbps Data Rate o 1A Low-Power Shutdown o High ESD Protection for RS-232 I/O Pins 15kV--Human Body Model 8kV--IEC 1000-4-2 Contact Discharge 15kV--IEC 1000-4-2 Air-Gap Discharge
MAX3322E/MAX3323E
Ordering Information
PART MAX3322E EUP MAX3323E EUE MAX3323EEPE TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 20 TSSOP 16 TSSOP 16 DIP
Pin Configurations
TOP VIEW
C1+ 1 V+ 2 C1- 3 C2+ 4 C2- 5 V- 6 TOUT2 7 RIN2 8 TOUT1 9 RIN1 10 20 VCC 19 GND 18 SHDN 17 VL
Applications
Bar-Code Scanners Video Security Industrial Data Acquisition Data Splitters
MAX3322E
16 RENABLE 15 TXENABLE 14 TIN2 13 ROUT2 12 TIN1 11 ROUT1
TSSOP Typical Operating Circuit and Functional Diagram appear at end of data sheet. Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND VCC, VL ....................................................................-0.3V to +6V V+ (Note 1) ....................................................(VCC - 0.3V) to +7V V- (Note 1) ................................................................+0.3V to -7V V+ + |V-| (Note 1) .................................................................+13V Input Voltages TIN_, RENABLE, TXENABLE, SHDN .....................-0.3V to +6V RIN_ ..................................................................................25V Output Voltages TOUT_............................................................................13.2V ROUT_........................................................-0.3V to (VL + 0.3V) Short-Circuit Duration TOUT_ to GND........................Continuous Continuous Power Dissipation (TA = +70C) 16-Pin DIP (derate 10.5mW/C above +70C) ............842mW 16-Pin TSSOP (derate 9.4mW/C above +70C) ........755mW 20-Pin TSSOP(derate 11mW/C above +70C) ..........879mW Operating Temperature Range MAX3322E/MAX3323E ...................................-40C to +85C Junction Temperature ..................................................... +150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = 3.0V to 5.5V, VL = 1.65V to 5.5V, C1-C4 = 0.1F, tested at +3.3V 10%; C1 = 0.047F, C2 = C3 = C4 = 0.33F, tested at +5V 10%; TA = TMIN to TMAX. Typical values are at VCC = VL = 3.3V and TA = +25C, unless otherwise noted.)
PARAMETER DC CHARACTERISTICS Supply Current Normal Operation Supply Current in Shutdown TRANSMITTER LOGIC INPUTS Input Logic Threshold Low Input Logic Threshold High Transmitter Input Hysteresis Input Leakage Current Input Logic Threshold Low Input Logic Threshold High Input Leakage Current RECEIVER OUTPUTS Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low VRIN VL = 1.65V VL = 3.3V VL = 5.0V -25 0.25 0.6 0.8 0.6 1.2 1.5 V +25 V IOL VOL VOH Receivers disabled, SHDN = 0V IOUT = 1.6mA, VL > 1.8V IOUT = 1mA, VL 1.8V IOUT = -1mA, VL > 1.8V IOUT = -500A, VL 1.8V VL - 0.4 VL - 0.1 VL - 0.4 VL- 0.1 +0.05 +10 0.4 0.4 A V V 2/3 x VL 0.01 1 IIL LOGIC INPUTS (TXENABLE, RENABLE, SHDN) 0.4 V V A VL 1.8V VL > 1.8V VL - 0.4 2/3 x VL 0.2 0.01 1 0.4 V V V A ICC ICC(SHDN) SHDN = VL, no load SHDN = 0V, no load 1 1 10 mA A SYMBOL CONDITIONS MIN TYP MAX UNITS
2
_______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.0V to 5.5V, VL = 1.65V to 5.5V, C1-C4 = 0.1F, tested at +3.3V 10%; C1 = 0.047F, C2 = C3 = C4 = 0.33F, tested at +5V 10%; TA = TMIN to TMAX. Typical values are at VCC = VL = 3.3V and TA = +25C, unless otherwise noted.)
PARAMETER Input Threshold High Input Hysteresis RENABLE = 1 Input Resistance TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current ESD PROTECTION Human Body Model RIN, TOUT IEC 1000-4-2 Air-Gap Discharge IEC 1000-4-2 Contact Discharge 15 15 8 kV All transmitter outputs loaded with 3k to ground VCC = V+ = V- = 0, TOUT_ = 2V, TXENABLE = 1 VOUT = 0V VOUT = 12V, transmitters disabled 5 300 5.4 10M 60 25 V mA A RIN RENABLE = 0 or SHDN = 0V, RIN from -13V to +13V 3 1 SYMBOL VL = 1.65V VL = 3.3V VL = 5.0V CONDITIONS MIN TYP 1 1.5 1.8 0.35 5 7 MAX 1.4 2.4 2.4 V k M V UNITS
MAX3322E/MAX3323E
TIMING CHARACTERISTICS
(VCC = 3.0V to 5.5V, VL = 1.65V to 5.5V, C1-C4 = 0.1F, tested at +3.3V 10%; C1 = 0.047F, C2 = C3 = C4 = 0.33F, tested at +5V 10%; TA = TMIN to TMAX. Typical values are at VCC = VL = 3.3V and TA = +25C, unless otherwise noted.)
PARAMETER Maximum Data Rate Receiver Propagation Delay Transmitter Propagation Delay Time to Enter Three-State on Tx Time to Exit Three-State on Tx Time to Enable Resistor Time to Disable Resistor Time to Enter Shutdown Time to Exit Shutdown Transmitter Skew Receiver Skew Transition Region Slew Rate RL = 3k to 7k, CL = 1000pF, measured from +3V to -3V or vice versa 6 tPHL tPLH tPHL tPLH SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching RIN_ to ROUT_, CL = 30pF, VL = 3.3V, Figure 2 TIN_ to TOUT_, RL = 3k, CL = 1000pF, Figure 1 (Note 2) (Note 2) (Note 2) (Note 2) MIN 250 150 180 0.6 0.7 10 3 0.4 0.2 50 50 100 30 30 50 50 10 10 TYP MAX UNITS kbps ns s s s s s s s ns ns V/s
Note 2: Guaranteed by design. Not production tested. _______________________________________________________________________________________ 3
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
Typical Operating Characteristics
(VCC = 3.3V, VL = 3.3V, C1-C4 = 0.1F, TA = +25C.) TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3322E toc01
SLEW RATE vs. LOAD CAPACITANCE
MAX3322E toc02
7.5 5.0 OUTPUT VOLTAGE (V) 2.5 0 -2.5 -5.0 DATA RATE = 250kbps LOAD = 3k IN PARALLEL WITH CL
18 15 SLEW RATESLEW RATE (V/s) 12 9 6 3 0 SLEW RATE+
-7.5 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF)
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE vs. DATA RATE
MAX3322E toc03
SUPPLY CURRENT vs. LOAD CAPACITANCE
LOAD = 3k ONE TRANSMITTER SWITCHING AT DATA RATE, OTHER TRANSMITTER AT 1/8 DATA RATE
MAX3322E toc04
7.5 5.0 OUTPUT VOLTAGE (V) 2.5 0 -2.5 -5.0 -7.5 0 50 100 150 200
40 250kbps
SUPPLY CURRENT (mA)
LOAD = 3k, 1000pF ONE TRANSMITTER SWITCHING AT DATA RATE, OTHER TRANSMITTER AT 1/8 DATA RATE
30
20
125kbps
10
40kbps
0 250 0 1000 2000 3000 4000 5000 DATA RATE (kbps) LOAD CAPACITANCE (pF)
RECEIVER INPUT RESISTANCE vs. INPUT VOLTAGE RANGE
MAX3322E toc05
RECEIVER INPUT RESISTANCE vs. INPUT VOLTAGE RANGE
RENABLE = 0 VL = 5V 4
MAX3322E toc06
5.50 RENABLE = 1 RECEIVER INPUT RESISTANCE (k) 5.25
5 RECEIVER INPUT RESISTANCE (M)
3
5.00
2
4.75
1
4.50 -25 -15 -5 VRIN (V) 5 15 25
0 -25 -15 -5 VRIN (V) 5 15 25
4
_______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
Pin Description
PIN MAX3322E 1 2 3 4 5 6 7, 9 8, 10 11, 13 12, 14 15 MAX3323E 1 2 3 4 5 6 7 8 9 10 11 NAME C1+ V+ C1C2+ C2VTOUT_ RIN_ ROUT_ TIN_ TXENABLE FUNCTION Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor +5.5V Generated by the Charge Pump Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor Positive Terminal of the Inverting Charge-Pump Capacitor Negative Terminal of the Inverting Charge-Pump Capacitor -5.5V Generated by the Charge Pump Transmitter Output Receiver Input Receiver Output Transmitter Input Transmitter Enable. Drive TXENABLE high to enable transmitter. Drive TXENABLE low to put transmitter into high impedance. Receiver Termination Enable. Drive RENABLE high for normal RS-232 5k termination. Drive RENABLE low to make receiver inputs high impedance. In either case, the receiver and its output are enabled. Logic-Level Supply. All CMOS inputs and outputs are referred to VL, which is from 1.65V to 5.5V. Shutdown Input. Drive SHDN low to put device into shutdown mode. Drive SHDN high for normal operation. In shutdown, all transmitter and receiver outputs are in three-state; receiver inputs are high impedance. Ground +3V to +5.5V Input Voltage. Bypass VCC to GND with a 0.1F capacitor.
MAX3322E/MAX3323E
16
12
RENABLE
17
13
VL
18 19 20
14 15 16
SHDN GND VCC
Detailed Description
The MAX3322E/MAX3323E are RS-232 transceivers for multidrop applications (i.e., multiple-receiver operation). The devices are pin selectable between standard RS-232 operation with 5k input resistance receivers or highinput-impedance receivers. Receivers of the MAX3322E/ MAX3323E remain active in both modes of operation. In multidrop applications, a selected receiver is set at a 5k input resistance, while the others are high-input impedance, maintaining RS-232 standards. Logic control permits selection of the functional mode: high impedance or normal load. The transmitters are enabled by logic control to allow transmission-line sharing. The logic supply input (VL) controls the levels of the system's I/O and works from 1.65V to 5.5V, providing compatibility with lower microprocessor I/O voltages. The transmitters are inverting level translators that convert CMOS logic levels into RS-232-compatible levels. They guarantee 250kbps with loads of RL = 3k and CL
= 1000pF. The transmitters are enabled or disabled (three-stated) by the logic control TXENABLE, which manages transmission-line sharing in multidrop applications. When TXENABLE is high, the transmitter is enabled. When TXENABLE is low, the transmitter is put in high-impedance state. The receivers can be used in two conditions, selectable by the logic control RENABLE. When RENABLE is high, the internal 5k resistor is connected across receiver input and ground. When RENABLE is low, the receiver input is high impedance, while maintaining receiving capability. In shutdown mode, all transmitter and receiver outputs are three-stated, receiver inputs are in high impedance, the charge pump is turned off, V+ decays to VCC, and V- decays to ground. ESD protection structures are incorporated in all pins to protect against ESD events encountered during handling and assembly. The receiver inputs and the transmitter outputs have 15kV ESD structure implementation.
5
_______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
+3V INPUT 0V 0V INPUT 50% +3V 50%
V+ OUTPUT 0V V-
OUTPUT
VCC 50% 50% GND
tPLH
tPHL
tPHL
tPLH
Figure 1. Transmitter Propagation-Delay Timing
Figure 2. Receiver Propagation-Delay Timing
POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER I/O CHIP POWER SUPPLY
SHDN
ing capacitor (C1, C2) and reservoir capacitor (C3, C4) to generate the V+ and V- supplies. Because supply voltages can vary from +3V up to +5.5V, the selection of the capacitor values depends on the V CC value. Table 2 shows minimum capacitor values.
RS-232 Transmitters
VL VL SHDN
MAX3322E
The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The transmitters are enabled or disabled (three-stated) by the logic control TXENABLE, which manages transmission-line sharing in multidrop applications. When TXENABLE is high, the transmitter is enabled. When TXENABLE is low, the transmitter is put in a highimpedance state (see Table 1).
RS-232
I/O CHIP WITH UART CPU
The MAX3322E/MAX3323Es' transmitters guarantee a 250kbps data rate with worst-case loads of 3k in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLinkTM). Transmitters can be paralleled to drive multiple receivers or mice. Figure 3 shows a complete system connection.
RS-232 Receivers
Figure 3. Interface Under Control of PMU
Dual Charge-Pump Voltage Converter
The MAX3322E/MAX3323Es' internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump), regardless of the input voltage (VCC), over a +3.0V to +5.5V range. The charge pumps operate in a discontinuous mode: if the output voltages are less than 5.5V, the charge pumps are enabled; if the output voltages exceed 5.5V, the charge pumps are disabled. Each charge pump requires a flyLapLink is a trademark of Traveling Software. 6
MAX3322E/MAX3323E receivers convert RS-232 signals to CMOS-logic output levels. The unique feature of the receivers is the switchable input resistance. The receiver input resistance can be 5k or high impedance. These two conditions are selectable by the logic control RENABLE. When RENABLE is high, the 5k resistor is connected across the receiver input and ground. When RENABLE is low, the receiver input is high impedance, maintaining receiving capability. This feature permits the design of multidrop applications, which observe RS-232 interface standards.
_______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
Table 1. Tx/Rx Logic
TXENABLE 1 1 1 1 0 0 0 0 RENABLE 1 1 0 0 1 1 0 0 SHDN 0 1 0 1 0 1 0 1 TRANSMITTER OUTPUT High-Z Active High-Z Active High-Z High-Z High-Z High-Z RECEIVER OUTPUT High-Z Enabled High-Z Enabled High-Z Enabled High-Z Enabled RECEIVER INPUT High-Z 5k High-Z High-Z High-Z 5k High-Z High-Z
5V/div
T2
2V/div
VL Logic Supply Input Unlike other RS-232 interface devices, in which the receiver outputs swing between 0 and V CC , the MAX3322E/MAX3323E feature a separate logic supply input (VL) that sets VOUT for the receiver outputs and sets thresholds for the transmit and shutdown inputs. This feature allows a great deal of flexibility in interfacing to many types of systems with different logic levels. Connect this input to the host logic supply (1.65V VL 5.5V). 15kV ESD Protection
To protect the MAX3322E/MAX3323E against ESD, transmitters and receivers have extra protection against static electricity to protect the device up to 15kV. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. ESD protection can be tested in various ways; the transmitter and receiver pins are characterized for protection to the following limits: * 15kV using the Human Body Model * 8kV using the IEC 1000-4-2 Contact Discharge method * 15kV using the IEC 1000-4-2 Air-Gap method Note: ESD performance depends on many conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. Human Body Model Figure 5 shows the Human Body Model, and Figure 6 shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5k resistor.
VCC = 3.3V C1-C4 = 0.1F 50s/div
T1
Figure 4. Transmitter Outputs when Exiting Shutdown
High-input impedance is guaranteed from -13.0V to +13.0V, when the receiver is in high-input-impedance mode. The receiver is able to withstand the RS-232 maximum input voltage of 25V.
Shutdown Mode
Supply current falls to less than 10A when the MAX3322E/MAX3323E are placed in shutdown mode (logic low). When in shutdown mode, the devices' charge pumps are turned off, V+ decays to VCC, V- is pulled to ground, the transmitter outputs and the receiver outputs are disabled (high impedance), and the receiver inputs are in high impedance (Table 1). The device enters shutdown when VL or VCC is absent. The time required to exit shutdown is typically 50s, as shown in Figure 4. Connect SHDN to VCC if shutdown mode is not used.
_______________________________________________________________________________________
7
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
RC 1M CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1.5k DISCHARGE RESISTANCE DEVICE UNDER TEST
IP 100% 90% AMPERES
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
Cs 100pF
STORAGE CAPACITOR
36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM
Figure 5. Human Body ESD Test Model
Figure 6. Human Body Model Current Waveform
IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not refer specifically to integrated circuits. The MAX3322E/ MAX3323E help the user design equipment that meets level 4 of IEC 1000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 1000-4-2 is a higher peak current in IEC 1000-4-2, because series resistance is lower in the IEC 1000-4-2 model. Hence, the ESD withstand voltage measured to IEC 1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7 shows the IEC 1000-4-2 model. Figure 8 shows the current waveform it generates when discharged into a low impedance. The Air-Gap Discharge test involves approaching the device with a charged probe. The Contact Discharge method connects the probe to the device before the probe is energized. Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. All pins require this protection during manufacturing. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports.
RC 50 to 100 CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE
RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST
Cs 150pF
STORAGE CAPACITOR
Figure 7. IEC 1000-4-2 ESD Test Model
I 100% 90%
Applications Information
The capacitor type used for C1-C4 is not critical for proper operation; polarized or nonpolarized capacitors can be used. The charge pump requires 0.1F capacitors for 3.3V operation. For other supply voltages, see Table 2 for required capacitor values. Do not use values smaller than those listed in Table 2. Increasing the capacitor values (e.g., by a factor of 2) reduces ripple
8 ____________________________________________________
10% t r = 0.7ns TO 1ns t 60ns
I PEAK
30ns
Figure 8. IEC 1000-4-2 ESD Generator Current Waveform
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
on the transmitter outputs and slightly reduces power consumption. The values of C2, C3, and C4 can be increased without changing C1's value. However, do not increase C1's value without also increasing the values of C2, C3, and C4 to maintain the proper ratios (C1 to the other capacitors). When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-.
Multidrop Applications
The MAX3323E connects to the RS-232 serial port of computer peripherals such as a bar-code scanner, video security controls, industrial multimeters, etc., and allows multiple devices to share the same communication cable connected to a PC. Figure 9 shows a PC UART transmitting to a single receiver with a 5k termination resistor while the other receivers remain in a high-impedance state. When the receiver inputs are high impedance, they remain active and maintain receiving capability. This feature permits the design of multidrop applications, which observe the RS-232 interface standard. Transmitters are enabled and disabled through TXENABLE, allowing the sharing of a single bus line. Transmitters are high impedance when disabled. The host PC's transmitter stays enabled at all times. Only one peripheral transmitter remains enabled at any time. If the host PC wants to communicate with another peripheral, it first must tell the current peripheral to deassert its transmitter.
MAX3322E/MAX3323E
Table 2. Minimum Required Capacitor Values
VCC (V) 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5 C1 (F) 0.1 0.047 0.22 C2, C3, C4 (F) 0.1 0.33 1
PC UART
MAX3323E
MAX3323E
MAX3323E
5k
5k
5k
PERIPHERAL CONTROL WITH UART
PERIPHERAL CONTROL WITH UART
PERIPHERAL CONTROL WITH UART
Figure 9. Multidrop Application _______________________________________________________________________________________ 9
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
+3.3V 0.1F SHDN C1 0.1F 1 C1+ 3 C14 C2 0.1F C2+ VCC V+ 2 C3 0.1F T1OUT 5V/div
MAX3322E fig11
T1IN 5V/div
MAX3323E
V-
6 C4 0.1F R1OUT 5V/div
5 C2-
T_IN
T_OUT 1000pF
VCC = 3.3V 2s/div
R_OUT
R_IN
Figure 11. Loopback Test Results at 125kbps
5k
MAX3322E fig12
GND
T1IN 5V/div
Figure 10. Loopback Test Circuit
T1OUT 5V/div
Power-Supply Decoupling
In most circumstances, a 0.1F bypass capacitor is adequate. In applications sensitive to power-supply noise, decouple VCC to ground with a capacitor of the same value as charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible.
VCC = 3.3V 1s/div
R1OUT 5V/div
Figure 12. Loopback Test Results at 250kbps
High Data Rates
The MAX3322E/MAX3323E maintain the RS-232 5.0V minimum transmitter output voltage even at high data rates. Figure 10 shows a transmitter loopback test circuit. Figure 11 shows a loopback test result at 125kbps, and Figure 12 shows the same test at 250kbps. For Figure 11, all transmitters were driven simultaneously at 125kbps into RS-232 loads in parallel with 1000pF. For Figure 12, a single transmitter was driven at 250kbps, and all transmitters were loaded with an RS-232 receiver in parallel with 1000pF.
Interconnection with 3V and 5V Logic
The MAX3322E/MAX3323E can directly interface with various 5V logic families, including ACT and HCT CMOS. The logic voltage power-supply pin VL sets the output voltage level of the receivers and the input thresholds of the transmitters.
10
______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
Typical Operating Circuit
+3.3V
Pin Configurations (continued)
TOP VIEW
C1+ 1 16 VCC 15 GND 14 SHDN
MAX3322E/MAX3323E
18 SHDN C1 0.1F 1 C1+ 3 C14 C2 0.1F C2+
20 VCC
17 VL V+ 2 C3 0.1F
V+ 2 C1- 3 C2+ 4 C2- 5
C4 0.1F 9 RS-232 OUTPUTS
MAX3323E
13 VL 12 RENABLE 11 TXENABLE 10 TIN1 9 ROUT1
MAX3322E
V-
6
V- 6 TOUT1 7 RIN1 8
5 C212 T1IN T1OUT
TTL/CMOS INPUTS
14 T2IN 15 16
T2OUT
7
TSSOP/DIP
TXENABLE RENABLE
ENABLE CONTROL VL
Functional Diagram
R1IN 10 C1+ C1- C2+ C2-
11 R1OUT
TTL/CMOS OUTPUTS VL 13 R2OUT
5k
RS-232 INPUTS
MAX3322E MAX3323E
VCC CHARGE PUMP
V+
R2IN 8
VVL 5k ROUT 5k HIGH IMPEDANCE RIN
GND 19 RENABLE
VL V+
Chip Information
TRANSISTOR COUNT: 1294 PROCESS: BiCMOS
TIN VSHDN TXENABLE
TOUT
______________________________________________________________________________________
11
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E/MAX3323E
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
12
______________________________________________________________________________________
15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX3322E/MAX3323E
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX3323E

	To Download MAX3323E Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .